James Crabtree is an associate editor of openDemocracy, and a senior policy analyst at NDN, a think tank in Washington DC.

"One popular thing to do in American politics is to note that the summers in the United States over the past few years have been very warm. As a result, global warming must be real. What's wrong with this reasoning?" So begins a scene in the recently released documentary Jesus Camp, showing a home-schooling evangelical mother teaching the basics of climate change. "It's only gone up 0.6 degrees!" replies her son Levi. He is reassured that this means "it's not really a big problem, is it?"

The mother impresses upon Levi that even if it's not a problem "it's a huge political issue, global warming is. And that's why it's really important for you to understand it." Problematically, she gets the politics of climate change upside down. Anyone with the scantest knowledge of science knows it is a problem. But a huge political issue? Hardly. Instead - even as the mid-term Congressional elections on 7 November 2006 approach - it's easy to avoid, tough to explain, and ruinously expensive to fix. In short, not much of a vote-winner.

James Crabtree is an associate editor of openDemocracy, and a senior policy analyst at NDN, a think-tank in Washington DC. He writes in an individual capacity

This year might have been different. Millions of Americans have seen Al Gore's An Inconvenient Truth, now the third most successful documentary in history. High gasoline (petrol) prices have focused voters' minds on the link between energy and security. The anniversary of hurricanes Katrina and Rita brought 2005's devastation back to the top of the political agenda. And, well, it's the biggest crisis facing the planet. That might count for something.

Yet the dots remain stubbornly unjoined. Editorial pages ignore the issue. Few politicians mention it, let alone campaign on it. And American's evening viewing is uninterrupted by advertisements featuring floods, melting glaciers or politicians riding husky sleds in the Arctic circle. Indeed, the Sierra Club, an environmental group, seems almost delusional in arguing that "concern about high gas prices, global warming ... and the influence of Big Oil ... have pushed energy and environmental issues to the forefront of election year politics."

Yes, $3 gas did worry Republican strategists. But the issue all but disappeared as pump prices fell in September. Few made the link between the rising cost of driving and rising temperatures. Energy security, meanwhile, is folded into a mélange of concerns that voters associate vaguely with either the economy (energy costs too much) or security (we are sending money to the terrorists.)

The non-event of Katrina is more puzzling. Environmental groups tried to make the connection with violent weather patterns, for instance by organising rallies in thirty American cities on 25 August. Yet any link got lost in the ferocious political battle to blame or exonerate President Bush.

And while American elections tend to be fought on local issues, campaigns can find clever ways to link larger issues to local concerns. Terrorists are unlikely to fly planes into the grain towers of rural Ohio, or blow up the McMansions of exurban Pennsylvania. But voters still think terrorism matters.

A Democratic failure

Environmental concerns have not been entirely absent from this election year. California's governor, Arnold Schwarzenegger, made headlines by agreeing a climate-change pact with Tony Blair on 31 July. In September he went further, signing a bill setting strict emissions-reduction targets. Yet Schwarzenegger's actions are best seen as a canny electoral strategy; a jump to the political centre in a state unusually sensitive to environmental issues. Few others have followed his lead.

Why? The public themselves bear some of the responsibility. Poll-driven American politicians respond smartly to their voters, with carefully crafted election-year messages. A dead issue is more likely born of public indifference than political blindness. And Americans are strikingly less concerned with climate change than their European counterparts. Roughly half of the population thinks the issue isn't a problem. Only four in ten blame manmade activity.

Blaming the public, though, only explains so much. Oddly, climate change could actually be seen as a perfect election-year issue. It allows high-minded politicians to make lofty speeches on the importance of saving the earth for our children. Yet it is sufficiently complex that no single congressman or senator could fairly be blamed for poor progress. Indeed, this type of debate - lofty rhetoric, little action - is roughly the approach of most European politicians.

America is different, and partisanship is at least part of the answer as to why. Concern about climate change divides along party lines. Democratic voters, much like Europeans, do think the issues matters. Only 23% of Republicans think it's important, but more than half of Democrats do. Yes, Democrats are ultimately more concerned with the war in Iraq, the threat of terrorism and the state of the economy. But they are also much more likely to find evidence of climate change compelling, and be convinced that manmade action is to blame. So while sceptics in the Bush camp might not be expected to speak up, perhaps Democratic wonks and strategists would step up?

Three recent examples suggest not. First, in July, Hillary Clinton released the results of her "American Dream Initiative", in partnership with the Democratic Leadership Council. She promised nothing less than the restoration of the nation's founding promise. Amongst many recommendations the report promoted a "strategic energy fund" to research clean technologies, but made no mention of climate change.

Second, in August, Democratic congressional supremo Rahm Emmanuel and policy wonk Bruce Reed released The Plan, a punchy, elegantly written election-year manifesto. The authors devoted an entire chapter to the "hybrid economy", but mentioned global warming only in passing.

Third, the Center for American Progress, the Democrats' biggest think-tank, has produced plenty on gas prices, but for the past six months has published no material on climate change.

A political vice

This leaves a conundrum. Climate change is a severe threat to America and the world. The evidence is overwhelming. Liberal voters - and arguably a growing number of conservatives - care about it. Yet it is largely ignored, even in the Democratic Party. Some cry conspiracy. Polls suggest that close to 40% of Americans think recent gas-price falls are attributable to political manipulation. Unlikely as this seems, others believe that the climate change no-show is the result of Democratic (in hoc to auto-friendly trade unions) and Republican (complicit with business in general) corruption. And there is some truth to this - climate change, at the very least, has to struggle for airtime against powerful, hostile political groups.

Yet, much the more interesting answer is rooted in the way the two American political parties fight elections. Put simply: Republicans run to the right, while Democrats run to the centre. And the environment gets lost in between.

President Bush and his party have become able to win elections on issues that appeal only to Republicans. This is why Senate leader Bill Frist felt able to clog up the recently Congress with measures to ban flag-burning, stop gay marriage, repeal the estate tax, and scupper abortions. The Democrats appeal to their own base much less frequently. Issues that motivate their supporters - abortion, inequality, the environment - are treated like dirty secrets.

There are complicated reasons for this. Conservative Republicans outnumber liberal Democrats, making appealing to them a more profitable electoral strategy. Republicans have better technology and turnout operations, meaning they are better able to communicate with their supporters and persuade to them vote. And there is a sense in which Democrats have become so electorally cautious that they fear the consequences of speaking up. One Capitol Hill staffer told me: "If you're a Democrat, the first half of every sentence you speak has to convince people you aren't a pussy. Once you've got past being tough on terrorists, or whatever, the issue you care about is always an after thought."

Whatever the explanation, the end result is that climate change is ignored, and god, guns and gays make all the headlines. Until the Democrats figure out how to campaign on issues that their supporters care about, so it will continue. We are left to hope that Levi's mother might just be right, and that eventually this huge political issue will get the coverage it needs. After all, even the evangelicals had to begin somewhere.